Various forms of dental attachment structure for the removable attachment and support of an appliance in the oral cavity are known to the prior art and have been known for quite some time. Typical of a rather early form of appliance is the dental attachment structure illustrated in U.S. Pat. No. 1,324,476 to S. G. Supplee. The Supplee patent, thus, discloses a dental attachment structure that includes a post member and a sleeve member. The post member is designed to be telescopically engaged by the sleeve member. The Supplee patent also discloses a lining received in position in the sleeve member by a cooperating dent and depression. This lining functions in the engagement of members in mounting of a partial denture in the oral cavity, and the engagement of structure is solely through frictional contact between the lining and the post member.
Another representative showing of the prior art is that of U.S. Pat. No. 1,664,726 to H. A. Adler. Without going into detail, it may be stated that Adler describes a dental attachment structure very similar to that described by Supplee. To this end, Adler describes a dental attachment structure including an independent metal leaf spring that provides frictional retention of cooperating members which theretofore were telescoped together. The dental attachment structures described by Supplee and Adler both are considered to suffer from problems of wear of the main components.
Another of the prior art teachings is described in U.S. Pat. No. 3,787,975 to M. Zuest. The Zuest patent discloses a dental attachment structure for removable attachment and support of either partial or full dentures in the oral cavity. The dental attachment structure includes an anchor formed with a socket at the base of a sleeve and a unit for support of the full or partial denture. The anchor is positioned within the root of a tooth that has been endodontically treated. The unit has a structure which is attached to the framework of the full or partial denture and a spherically shaped head which is adapted for removable receipt in the socket.
Still another of the prior art teachings is described in U.S. Pat. No. 3,991,472 to F. Lukesch. The Lukesch patent relates to a denture providing a ball and socket connection between an anchor, and the combination of a plate which supports the prothesis and a pin with a slotted ball-shaped projection which extends from the plate. The pin is threaded at the other end for support in a threaded bore in the plate and the slots provide a spring action for snapping the prothesis into the anchor.
One further representation of the prior art in the field of dental attachment structures is set out in U.S. Pat. No. 4,362,509 which issued to the inventor of the dental attachment structure to be fully discussed below. This patent describes a dental attachment structure which includes a male member permanently mounted either to the partial denture, overdenture or bridgework for receipt in the oral cavity or to a natural tooth within the oral cavity itself. The female member is mounted to the other of the structures. An element of a resilient material is received on and mechanically latched either to the male member or the female member to reside between and in surface-to-surface contact with an extension of the male member and the wall of a pocket in the female member.
The structures described in the patents to Supplee, Adler and Zuest suffer from various problems and disadvantages. The most important disadvantage is the requirement of repair or replacement of the attachment structure in the event that the contact surfaces become worn. Wear of the contact surfaces results from the manner of attachment and support of the appliance within the oral cavity. The Supplee lining is described as formed of metal and most likely a hard metal to provide the characteristic of elasticity or spring required for retention. In use of the appliance over a period of time, and repeated insertion and removal, there will be wearing of the post member which ultimately will require repair or reconstruction of the appliance. The Supplee device is considered to suffer from a further problem, namely a problem that develops from a required shortening of the post member to facilitate mounting to the abutment tooth which may also be short. This shortening of the post member and consequently the sleeve member reduces the area of contact between the lining and the post member resulting in a limited frictional retention.
The problem of wear is considered, also, to manifest itself in the Lukesch structure. In addition, the Lukesch structure is considered to suffer from another disadvantage namely that the slots in the ball-shaped projection result in a weakening in the integrity of the pin. As to the consideration of wear, the routine of inserting and removing the denture several times a day will cause wear along the contacting surfaces of the anchor, and in time, sometimes only in a matter of weeks, these repeated insertions and removal may result in loss of snap retention. And, while there is the capability of replacing the pin with a new pin, it may be difficult to thread a new pin into the plate to extend to exactly the same location as the pin it replaces. Even a small deviation will result in problems with the pin not properly engaging the anchor when the denture is seated.
Wear of contact surfaces is also a problem in the dental attachment structure of Zuest. Zuest, unlike Supplee and Adler, employs no lining or similar structure. Wear of the surface of either or both of the anchor and unit may result and require replacement of the entire component.
The dental attachment structure disclosed in my prior patent addresses the problem of wear of components by adding a replaceable layer of plastic in the form of a sleeve lining or similar structure. The sleeve lining carries mechanical latching elements to interact with a complementary structure, whether it is the female or male member to which it is attached to become a unit, as well as with the other of those members to reside therebetween when the male and female members are mounted together. The mechanical latching elements which unitize the sleeve lining and a member provide a latching force greater than the latching force to maintain the mounted condition of the male and female members. In this manner, the sleeve lining will remain on the appliance when the appliance is removed from the oral cavity.